Colorant film for aluminum surfaces



Oct. 22, 1968 T. J. HURLEY ET AL 3,407,098

COLORANT FILM FOR ALUMINUM SURFACES Filed Aug. 25, 1965 INVENTORS.THOMAS J. HURLEY MART/IV A. ROBINSON JAMES A. SCRUGGS 62y A NT UnitedStates Patent f 3,407,098 COLORANT FILM FOR ALUMINUM SURFACES Thomas JHurley, Madison, Martin A. Robinson, Orange, and James A. Scruggs, WestHaven, Conn., assignors to Olin Mathieson Chemical Corporation,acorporation of Virginia r 1 Filed Aug. 25, 1965, Ser. No. 482,545 11Claims. (Cl. 148-6.1)

This invention relates to a novel class of coordination compounds, theirsynthesis and use. The novel compounds are useful for coloring aluminum.More particularly the vnovel compounds ofthis invention are-bis[3-(3-alkoxylH-isoindol-l-imino)-1H-isoindol-1-irninato] nickel II)having the formula shown in theaccompanying drawing where R is alkyl of1 to 6 carbons, suitably methyl, ethyl, isopropyl, n-butyl, n-amyl, sec.amyl and neohexyl.

I 'Dyeings possessing some acceptable'light-fastness are achieved onanodized aluminum when the aluminum is properly anodized and the surfacesealed after dyeing by treating it with boiling water or steam.Heretofore, anodized aluminum has usually been dyed with various dyes inaqueous or non-aqueous solution. In aqueous dyeing, the depth of shadeis often limited, and the colored alminum is not sufficiently light-fastto make it useful for exterior applications under weathering conditions.Aqueous dyeing procedures require extended periods of dyeing to obtaindeep penetration into the oxide coating on the aluminum and it isgenerally necessary to follow the initial dyeing'by treatment at highertemperatures or otherwise to seal the coating and stop the dyeabsorption.

Certain phthalocyanines have been applied to anodized aluminum to colorit, but it is highly desirable to provide an improvedprocess forcoloring aluminum to obtain permanently pigmented aluminum.

One object of the present invention is to synthesize the novel nickelcomplexes defined above.

Another object of the present invention is to provide an improvedprocess for coloring anodized aluminum with a strongly adherentcoatinghaving excellent fastness to light. Other objects appearhereinafter.

The objects of this invention are accomplished by the 7 improved processof the present invention for coloring anodized -aluminum' whichcomprises synthesizing the novel nickel compounds and applying them tothe aluminum to. be colored. By means of thepresent invention it is nowpossible to color aluminum to form a colored surface on the metal whichis remarkably adherent, stable and light fast. Compared to the coloredaluminum or prior art, processes, the. process of this invention isvastly superior. The aluminum coloring process of this invention isdevoid of the numerous problems associated with the prior artprocedures. The colored anodized aluminum displays a light fastness ofat least 1000 Fade-O- Meter hours with no change in intensity.Previously, a light fastness of 500 Fade-O-Meter hours was consideredsatisfactory. The nickel compounds of this invention are also useful ascolorants for paper, textiles and other metals, particularly aluminumalloys which are anodized by aluminum anodizing processes.

The novel compounds of this invention are prepared by the reaction ofnickel (II) salts and 1,3-diiminoisoindoline, preferably in thestoichiometric ratio of about 4 grams moles of the diiminoisoindoline to1 gram mole of nickel (II) salt. This ratio can vary considerably, forexample, from 1:1 to 8:1. Excess reactant, however, remains to beseparated from the desired product. The reaction is carried out in alarge excess of an aliphatic alcohol having the formula ROH, where R hasthe same meaning as defined above, suitably at the reflux temperature ofthe alcohol. The molar ratio of alcohol to 1,3- diiminoisoindoline isappropriately from about 5:1 to

30:1. The smaller ratios of alcohol advantageously permit cooling thereaction mixture and recovery of the precipitated product directlywithout evaporating excess alcohol. The reaction is rapid and issubstantially completed usually in 10 minutes. The reaction time mayvary from about 5 to 60 minutes or longer. The product is suitablyrecovered directly by cooling the reaction mixture or by evaporation ofthe excess alcohol and extraction of the residue to dissolve the nickelcompound and to leave by-product ammonium chloride as an insolubleresidue. Suitable extractants include heptane, octane, petroleum ether,chloroform, toluene, xylene, o-dichlorobenzene and1,2,4-trichlorobenzene. The extractant is removed by vacuum evaporationand the nickel product is suitably recrystallized, for example, fromacetone or alcohol.

The nickel salt used in the preparation of the novel compounds of thisinvention is suitably introduced in the form of any of various salts,for example, nickel (II) chloride, oxide, nitrate, sulfate or acetate.The anhydrous salts are preferred.

For the aluminum-coloring process of this invention, the novel nickelcompounds of this invention are dissolved in a suitable solventincluding aliphatic and aromatic hydrocarbons and hal'ohydrocarbonshaving boiling points at atmospheric pressure above about C. Examplesinclude heptane, octane, petroleum ether, kerosene, Nujol, toluene,xylene, o-dichlorobenzene and 1,2,4- trichlorobenzene. Nujol isparticularly advantageous and is preferred for its high flash point andboiling point. A concentration of the nickel compound of from 0.1 to1.0% is suitable. On heating the anodized aluminum to be colored incontact with the solution of the novel nickel compound at temperaturesfrom 100 to 150 C., the aluminum gradually becomes colored. The colordeepens with time but reaches a maximum intensity usually in about 10minutes. Longer contact of the aluminum with the solution produces nodeeper coloration.

The aluminum coloring process of the present invention is amenable tocontinuous operation by various modifications. Loose coils of anodizedaluminum sheet are appropriately immersed in a container, for example, adegreasing tank containing the colorant mixture, continuously orintermittently replenished, until the metal is sufficiently coated. Thefinished coil is removed and replaced by a fresh coil of anodizedaluminum. Alternatively a solution of the colorant is sprayed on amoving strip of metal which passes through a suitably heated zone with aholding time therein suflicient to produce a coating of the desireddepth of color.

EXAMPLE I A mixture of 2.6 g. (0.02 mole) of anhydrous nickel (II)chloride and 625 ml. of n-butyl alcohol was heated to reflux temperaturewith stirring. To the suspension was added rapidly a solution of 11.7 g.(0.08 mole) of 1,3-diiminoisoindoline in 125 ml. of boiling butanol. Themixture was refluxed and stirred for 10 minutes. The dark red mixturewas filtered hot and the filtrate was vacuum evaporated to remove thebutanol. The red solid residue was extracted with hot toluene andfiltered. Toluene was removed from the filtrate by vacuum evaporationand the red solid residue was crystallized from acetone. The yield ofbis[3 (3 n butoxy 1H- isoindol 1 imino) 1H isoindol 1 iminato] nickel(II) was 9.6 g. or 67% of theoretical.

Analysis for C H N O Ni.-Calcd.: C, 66.95; H,-

4.74; N, 15.62. Found: C, 66.73; H, 5.17; N, 15.80.

EXAMPLE II A 0.75% solution of the product of Example I in Nujol washeated to C. in contact with a piece of un- EXAMPLE III A mixture of 1.3g. (0.1 mole) of anhydrous nickel (II) chloride and 300 ml. of n-amylalcohol was refluxed and a solution of 5.8 g. (0.04 mole) of 1,3diiminoisoindoline in 100 ml. of boiling amyl alcohol was added rapidly.The mixture was refluxed and stirred for minutes and the bis[3 (3 namyloxy 1H isoindol- 1 imino) 1H isoindol 1 iminato] nickel (II)compound was isolated by the method described in Example I. Yield 6.1 g.or 85% of theoretical.

Analysis for C H N O Ni.Calcd.: C, 67.65; H, 5.10; N, 15.03. Found: C,67.45; H, 5.47; N, 15.27.

EXAMPLE IV The product of Example III was applied to anodized aluminumas described in Example II With essentially the same results.

EXAMPLE V The procedure of Example I was repeated using 5.4 g. (0.03mole) of anhydrous nickel (II) acetate and 11.7 g. (0.08 mole) of1,3-diiminoisoindoline to produce the same bis[3 (3 n butoxy 1H isoindol1 imino)- 1H isoindol l iminato] nickel (II) compound in a yield of 60%based on the isoindoline.

EXAMPLE VI A slurry of 6 g. (0.46 mole) of anhydrous nickel (II)chloride in 1500 ml. of n-butanol was brought to reflux and a hotsolution of 232 g. (1.60 moles) of 1,3-diiminoisoindoline in 2250 ml, ofn-butanol was added quickly with stirring. The resulting red solutionwas held at reflux and stirred vigorously for 20 minutes. The solutionwas filtered hot and then cooled in a refrigerator. The bis[3 (3 nbutoxy 1H isoindol 1 imino)- lH isoindol 1 iminato] nickel (II) whichprecipitated was removed by filtration and amounted to 143 g. or 50% ofthe theoretical yield. The remaining solution was evaporated to drynessand the red solid residue was dissolved in hot chloroform and filteredto remove ammonium chloride. The filtrate was evaporated to dryness. Theresidue was washed with cold methanol and recrystallized from acetone.An additional 60 grams of product was obtained. The total yield was 71%of theoretical.

What is claimed is:

1. Bis[3 (3 alkoxy 1H isoindol l imino)- lH isoindol 1 iminato] nickel(II) in which said alkoxy contains 1 to 6 carbons.

2. Bis[3 (3 l butoxy 1H isoindol l imino)- lI-I isoindol iminato] nickel(II).

3. Bis[3 (3 amyloxy 1H isoindol 1 imino)- lH isoindol l iminato] nickel(II).

4. Process for the preparation of bis[3 (3 alkoxy- 1H-- isoindol 1imino) 1H isoindol -'1 --iminato] nickel (II) in which said alkoxycontains 1 to 6 carbons by refluxing a mixture of nickel (II) salt and1,3-diiminoisoindoline in an aliphatic alcohol of 1 to 6 carbons andseparating the resulting nickel complex from the reaction mixture. A, "I

5. The process of claim 4 in which the nickel (II) salt is nickel (II)chloride, oxide, nitrate, sulfate or acetate.

6. The process of claim 4 in which the molar ratio of1,3-diiminoisoindoline to nickel (II) salt is from 1:1 to 8:1.

7. The process of claim 6 in which said molar ratio is substantially4:1.

8. The process of claim 4 in which the molar ratio of said aliphaticalcohol to diiminoisoindoline is from 5:1 to 30: 1.

9. Method of coloring aluminum which comprises heating unsealed anodizedaluminum at to C. in contact with a solution of bis[3 (3 alkoxy- 1Hisoindol 1 imino) 1H isoindol 1 iminato] nickel (II) in which saidalkoxy contains 1 to 6 carbons in an aliphatic or aromatic hydrocarbonor halohydrocarbon having a boiling point above about 100 C. atatmospheric pressure. w

10. Aluminum having adherent on the surface thereof a colorant film ofbis[3 (3 alkoxy 1H isoindol- 1 imino) lH isoindol l iminato] nickel (II)in which said alkoxy contains 1 to 6 carbons.

11. Aluminum having adherent on the surface thereof a colorant filmproduced by heating unsealed anodized aluminum at 100? to 150 C. incontact with a solution of bis[3 (3 alkoxy 1H isoindol 1 imino) 1H-isoindol 1 iminato] nickel (II) in which said alkoxy contains 1 to 6carbons in an aliphatic or aromatic hydrocarbon or halohydrocarbonhaving a boiling point above about 100 C. at atmospheric pressure.

References Cited UNITED sTATEs PATENTS 2,739,155 3/1956 Rosch et al. 260326.1 3,023,164 2/1962 Lawton et a1 148-6.1 x 3,026,220 3/1962 Sowards6t al. 148--6.1 3,114,660 12/1963 Cochran 1486.1 3,326,728 6/1967Robinson 1486.1

FOREIGN PATENTS 297,833 4/1954 Switzerland.

RALPH S. KENDALL, Primary Examiner.

9. METHOD OF COLORING ALUMINUM WHICH COMPRISES HEATING UNSEALED ANODIZEDALUMINUM AT 100* TO 150*C. IN CONTACT WITH A SOLUTION OF BIS(3 - (3 -ALKOXY - 1HISOINDOL - 1 - IMINO) - 1H - ISOINDOL - 1 - IMINATO) NICKEL(II) IN WHICH SAID ALKOXY CONTAINS 1 TO 6 CARBONS IN AN ALIPHATIC ORAROMATIC HYDROCARBON OR HALOHYDROCARBON HAVING A BOILING POINT ABOUTABOUT 100*C. AT ATMOSPHERIC PRESSURE.